Dash Lights not working

[bhermes]

I have been posting on another thread about dash removal but thought I would post here. I have no dash lights.....

I have removed the dash.

I looked at one of the bulbs and it appeared to be good. I put a meter on the bulb and got approximately 5.4 ohms. I think this means the bulb is not bad.

I also jumped across the green with white strips and the white with red strip on the combo switch with no success in getting dash lights to come on. Note here, all other lights work.

I figured the next thing to test is the rheostat dimmer switch. I have seen a few write ups but don't exactly understand how to check. If someone can give me the novice version that would be great.

What else should I check?

Thanks.

[SteveJ]

Look at the BE section of the FSM. It will have a breakout for the circuit. I don't have time to look at it right now, but that is the best source to figure out how to test the circuit in the car. By the way, are the running lights turning on?

[bhermes]

Got it. Looked through the BE section of FSM and on page BE-29 it contains the removal procedure and that in the on position the reading should be between 0 and 10 ohms.

I will be checking the connection and the ohm check and will see if this may be an issue.

Thasnks.

[bhermes]

Also, running lights work, voltage gauge works, map light works. Fuel gauge does not work. Just some additional info.

[Marty Rogan]

Check your fuse box, third one down on the right side. It is common for that one to melt down the fuse box and take out the dash lights. Your tail lights will be out too.

Marty

[SteveJ]

Got it. Looked through the BE section of FSM and on page BE-29 it contains the removal procedure and that in the on position the reading should be between 0 and 10 ohms.

I will be checking the connection and the ohm check and will see if this may be an issue.

Thasnks.

Actually, look at BE-17. It gives you a breakout of just the dash lights.

Check your fuse box, third one down on the right side. It is common for that one to melt down the fuse box and take out the dash lights. Your tail lights will be out too.

Marty

For the 280Z, it's the top fuse on the right. In the 260Z & 280Z for some reason, it wasn't the fuse box melting as much as it was green/white wire overheating at the connector.

[bhermes]

OK. I am really trying to learn here but have never spent much time with electrical stuff.

From the diagram I see the top right fuse tying into the C-2 connector and then to the combo switch and then basically a common GW wire to the lights. Among other things. I will recheck fuses but I think they are all good.

I think I can read the diagram but I am just not sure how to test things to see where the issue may be. If you can just get me started maybe I can then run with the information.

Sorry just not knowledgeable here. Someone said in another message it is because I am a Mechanical Engineer by trade and now a teacher. Sadly to say I teach a high school engineering class that requires me to teach a section on electrical circuits.

Any direction what be great.

[SteveJ]

There are basically three ways to troubleshoot a simple circuit like this:

1. at the beginning

2. in the middle

3. at the end

Number 1 won't be that effective. If the running lights work, then we know that the beginning of the circuit is intact.

Number 2 isn't easy to track unless you follow the full wiring diagram and find where the G/W wire branches off between the dash lights and running lights.

Number 3 implies a loss of ground. Unplug the connector at the rheostat. Check the black wire in the dash harness at that connector for continuity with the chassis. If you can remove the speedometer or tachometer you can check for continuity at the dash harness connectors for the R/L wire to the rheostat connector in the dash harness.

Since the R/L is show as being daisy-chained in the dash harness, if the rheostat tested good, it's probably a grounding issue.

[bhermes]

This is where I get in trouble. I measured the rheostat off and got 1 on the 200 ohm setting. At fully turned clockwise I got .8. I measured the harness side black wire to the body chassis and got 1 on the 200 ohm setting.

Not sure what this means but I thought I should have gotten 10 on the rheostat when turned CW.

Thanks in advance.

[bhermes]

Another question, is there a way to jumper past the rheostat dimmer switch just to see if the lights come on?

Also, if I do need a new switch where can I get one?

Thanks.

[SteveJ]

Unplug the rheostat and put a jumper across the terminals in the dash harness where the rheostat was plugged in. It's just as easy as that.

[bhermes]

I jumped across the dash side of the rheostat and still no dash lights. I am about to give up for now and put the thing back together. It appears that the rheostat is bad but something else is also an issue.

Any last thoughts. May have to attack this later in the summer.

Thanks.